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[2003:cb:c708:f600:abad:360:c840:33fa]) by smtp.gmail.com with ESMTPSA id h9-20020a05600c28c900b003a5dfd7e9eesm2106499wmd.44.2022.08.26.03.49.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Aug 2022 03:49:38 -0700 (PDT) Message-ID: <411d7b8c-f914-875e-b397-856e6a894366@redhat.com> Date: Fri, 26 Aug 2022 12:49:37 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.12.0 To: Peter Xu , linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Andrew Morton , Huang Ying , stable@vger.kernel.org, Yu Zhao References: <20220823221138.45602-1-peterx@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH] mm/mprotect: Only reference swap pfn page if type match In-Reply-To: <20220823221138.45602-1-peterx@redhat.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1661510985; a=rsa-sha256; cv=none; b=FS0XHk/g8A9kLkTXRgSSXmUHDm/nfZ+mhaDg+iWb/nMcp3rwuh9Bj2kpfIjliqydQHwfR4 XpWjZZqE3LzLsoCjcVlHV3mmgom1Vsz9BdcVREjlCxebOML1nuA5GTDYBwjweoNGYLkNvf iW7fZxNZbuV6lfvDM5QXdmIKNMRrykk= ARC-Authentication-Results: i=1; imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Tru9o3FT; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf27.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1661510985; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=Eg7Ryqgl4/7psa0mDnwJcUX72EbQV3JdNEdy3KuxwWs=; b=m6xd8WG+ofjrd64VQVRfWoF6yZ+u1FOYNaGYeLko0A6HlHzXicpps3j9XLVt0C/l5A2vMz XpxKLWpyPxzV0IxVvZEB8rsDgLKd8EccblZ4fbDVYJNXj2DvaV7issGoIEA1GmvKrk6uGF KIsg/YHlBFJJZg0I0ezgRtMR/87tBwY= Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=Tru9o3FT; dmarc=pass (policy=none) header.from=redhat.com; spf=pass (imf27.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com X-Rspam-User: X-Rspamd-Queue-Id: 0854840027 X-Rspamd-Server: rspam08 X-Stat-Signature: o7p4dyuy8hzk4cfqhddaaxfjtckq944d X-HE-Tag: 1661510984-673208 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 24.08.22 00:11, Peter Xu wrote: > Yu Zhao reported a bug after the commit "mm/swap: Add swp_offset_pfn() to > fetch PFN from swap entry" added a check in swp_offset_pfn() for swap type [1]: > > kernel BUG at include/linux/swapops.h:117! > CPU: 46 PID: 5245 Comm: EventManager_De Tainted: G S O L 6.0.0-dbg-DEV #2 > RIP: 0010:pfn_swap_entry_to_page+0x72/0xf0 > Code: c6 48 8b 36 48 83 fe ff 74 53 48 01 d1 48 83 c1 08 48 8b 09 f6 > c1 01 75 7b 66 90 48 89 c1 48 8b 09 f6 c1 01 74 74 5d c3 eb 9e <0f> 0b > 48 ba ff ff ff ff 03 00 00 00 eb ae a9 ff 0f 00 00 75 13 48 > RSP: 0018:ffffa59e73fabb80 EFLAGS: 00010282 > RAX: 00000000ffffffe8 RBX: 0c00000000000000 RCX: ffffcd5440000000 > RDX: 1ffffffffff7a80a RSI: 0000000000000000 RDI: 0c0000000000042b > RBP: ffffa59e73fabb80 R08: ffff9965ca6e8bb8 R09: 0000000000000000 > R10: ffffffffa5a2f62d R11: 0000030b372e9fff R12: ffff997b79db5738 > R13: 000000000000042b R14: 0c0000000000042b R15: 1ffffffffff7a80a > FS: 00007f549d1bb700(0000) GS:ffff99d3cf680000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000440d035b3180 CR3: 0000002243176004 CR4: 00000000003706e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > > change_pte_range+0x36e/0x880 > change_p4d_range+0x2e8/0x670 > change_protection_range+0x14e/0x2c0 > mprotect_fixup+0x1ee/0x330 > do_mprotect_pkey+0x34c/0x440 > __x64_sys_mprotect+0x1d/0x30 > > It triggers because pfn_swap_entry_to_page() could be called upon e.g. a > genuine swap entry. > > Fix it by only calling it when it's a write migration entry where the page* > is used. > > [1] https://lore.kernel.org/lkml/CAOUHufaVC2Za-p8m0aiHw6YkheDcrO-C3wRGixwDS32VTS+k1w@mail.gmail.com/ > > Fixes: 6c287605fd56 ("mm: remember exclusively mapped anonymous pages with PG_anon_exclusive") > Cc: David Hildenbrand > Cc: > Reported-by: Yu Zhao > Signed-off-by: Peter Xu > --- > mm/mprotect.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/mprotect.c b/mm/mprotect.c > index f2b9b1da9083..4549f5945ebe 100644 > --- a/mm/mprotect.c > +++ b/mm/mprotect.c > @@ -203,10 +203,11 @@ static unsigned long change_pte_range(struct mmu_gather *tlb, > pages++; > } else if (is_swap_pte(oldpte)) { > swp_entry_t entry = pte_to_swp_entry(oldpte); > - struct page *page = pfn_swap_entry_to_page(entry); > pte_t newpte; > > if (is_writable_migration_entry(entry)) { > + struct page *page = pfn_swap_entry_to_page(entry); > + > /* > * A protection check is difficult so > * just be safe and disable write Stumbling over the THP code, I was wondering if we also want to adjust change_huge_pmd() and hugetlb_change_protection. There are no actual swap entries, so I assume we're fine. diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 482c1826e723..466364e7fc5f 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1798,10 +1798,10 @@ int change_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, #ifdef CONFIG_ARCH_ENABLE_THP_MIGRATION if (is_swap_pmd(*pmd)) { swp_entry_t entry = pmd_to_swp_entry(*pmd); - struct page *page = pfn_swap_entry_to_page(entry); VM_BUG_ON(!is_pmd_migration_entry(*pmd)); if (is_writable_migration_entry(entry)) { + struct page *page = pfn_swap_entry_to_page(entry); pmd_t newpmd; /* * A protection check is difficult so diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 2480ba627aa5..559465fae5cd 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6370,9 +6370,9 @@ unsigned long hugetlb_change_protection(struct vm_area_struct *vma, } if (unlikely(is_hugetlb_entry_migration(pte))) { swp_entry_t entry = pte_to_swp_entry(pte); - struct page *page = pfn_swap_entry_to_page(entry); if (!is_readable_migration_entry(entry)) { + struct page *page = pfn_swap_entry_to_page(entry); pte_t newpte; if (PageAnon(page)) @Peter, what's your thought? -- Thanks, David / dhildenb